我想要获取所有相册的图片。我正在通过web服务获取此信息。 Web服务具有以下布局。NSFetchRequest不会回报任何东西
{
"name": "Club Brugge - KRC Genk",
"date": "08.10.2012",
"albumId: 1,
"pictures": [
{
"pic_album_id"=1,
"pic_id" = 1,
"url": "http://www.krcgenk.be/images/gallery/album_199/800X600/1a06dc0e405fd0219e3d327f1eec7fbf.jpg"
},
{
"pic_album_id"=1,
"pic_id" = 2,
"url": "http://www.krcgenk.be/images/gallery/album_199/800X600/e8e10c0664eb0533a0534ed69891b165.jpg"
},
{
"pic_album_id"=1,
"pic_id"= 3,
"url": "http://www.krcgenk.be/images/gallery/album_199/800X600/750b55a87b8eae33b8f3278add9bec44.jpg"
}
]
我有以下功能获取某个相册的所有图片。
- (NSMutableArray *)getAllPicturesOfAlbumId: (int)AlbumId
{
NSString *picture_Url = [[NSString alloc]init];
NSArray *results = [[NSArray alloc]init];
_picturesForAlbum = [[NSMutableArray alloc]init];
picture_Url = @"";
NSFetchRequest *request = [[NSFetchRequest alloc] init];
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"pic_album_id == %@",
[NSNumber numberWithInt:AlbumId]];
NSLog(@"album id: %@",[NSNumber numberWithInt:AlbumId]);
[request setEntity:[NSEntityDescription entityForName:@"Picture" inManagedObjectContext:self.genkDatabase.managedObjectContext]];
[request setPredicate:predicate];
NSError *error = nil;
results = [self.genkDatabase.managedObjectContext executeFetchRequest:request error:&error];
NSLog(@"results: %@",results);
if (results == nil) {
NSLog(@"nil results");
// handle errors
} else if (results.count == 0) {
NSLog(@"0 results");
// nothing found
} else {
for(int i = 0; i < results.count ; i++){
Picture *picture = [results objectAtIndex:i];
NSLog(@"%@",[results objectAtIndex:i]);
[_picturesForAlbum addObject:picture];
}
}
NSLog(@"%@",_picturesForAlbum);
//NSLog(@"album: %@",[_picturesForAlbum objectAtIndex:5]);
return _picturesForAlbum;
}
上面的代码给出了以下日志。 (我给了testcase AlbumId = 3)
2012-10-12 14:53:04.577 RacingGenk[4793:c07] album id: 3
2012-10-12 14:53:04.578 RacingGenk[4793:c07] results: (
)
2012-10-12 14:53:04.578 RacingGenk[4793:c07] (
)
希望有人能帮助我。
亲切的问候。
**这里你可以看到我的数据库模型
编辑
这里你可以看到我是如何得到我的照片,并把它放在我的数据库的screenshot。
+ (Picture *)pictureWithGenkInfo:(NSDictionary *)genkInfo
inManagedObjectContext:(NSManagedObjectContext *)context
withAlbumId:(int)albumId
withPictureId:(int)pictureId;
{
Picture *picture = nil;
picture = [NSEntityDescription insertNewObjectForEntityForName:@"Picture"
inManagedObjectContext:context];
picture.url = [genkInfo objectForKey:PICTURES_URL];
picture.pic_album_id = [NSNumber numberWithInt:albumId];
picture.picture_id = [NSNumber numberWithInt:pictureId];
return picture;
}
//上面的方法在我的第一个控制器中调用一个屏幕。有了这个循环,我填补了我的核心数据库。
for (NSDictionary *genkInfo in albums) {
albumId++;
[Album albumWithGenkInfo:genkInfo inManagedObjectContext:document.managedObjectContext withAlbumId:albumId];
for (NSDictionary *genkInfo2 in pictures) {
pictureId++;
[Picture pictureWithGenkInfo:genkInfo2 inManagedObjectContext:document.managedObjectContext withAlbumId:albumId withPictureId:pictureId];
}
pictureId = 0;
// table will automatically update due to NSFetchedResultsController's observing of the NSMOC
}
这很奇怪,你从图片实体获取结果,但是使用谓词相册ID。我认为在谓词应该是:[NSPredicate predicateWithFormat:@“album.pic_album_id ==%@”,numberWithInt:AlbumId]]; – NeverBe
对不起,我提供了错误的json数据。我编辑了我的代码。 – Steaphann
你有没有Album实体?这个实体应该有图片一对多的关系。然后你可以得到所有picuture只是调用 - > NSArray *图片= [album.pictures allObjects]; – NeverBe